Stanford graduate students solve the silent Prius problem

I live in a Prius neighborhood. In the short two-block walk to the local elementary school this morning, I counted six. In general, I think that's a good thing.

I also live in a "playborhood", that's a new word for a retro idea: a neighborhood in which kids play unorganized pickup games outside, sometimes (OK, a lot of times) in the street. In general, I also think this is a good thing.

But combine these two trends, and, in the eyes of a worried mom, you've got an accident waiting to happen. The kids are pretty good about listening for a car turning onto our street and scoot to the sidewalks. But a Prius operating in electric mode is virtually silent.

Besides being a threat to kids playing in the street, the silent car is a nightmare for blind pedestrians. Concern about silent car dangers led to the introduction of the so-called "Bell the Hybrid" Act, a.k.a. the Pedestrian Safety Act of 2008, HR 5734, introduced in April which, if it passes, would direct the Secretary of Transportation to establish a motor vehicle standard that would alert pedestrians to a car's approach.

That wouldn't be hard; there are a number of ways one could do this; heck, kids have

been clipping playing cards to make their bicycles buzz for generations. One suggestion is a radio transmitter that sends a signal to some sort of buzzer carried by the blind. That's unlikely to fix the kid-in-the-street hazard, however.

Another approach is already in prototype and going on the road this summer to conferences aimed variously at the auto industry or the vision impaired. Called the PANDA system, or "Pedestrian Awareness Noiseâ''Ã'Ã¬emitting Device and Application," it comes from Enhanced Vehicle Acoustics, a corporate name for two Stanford University graduate students, Bryan Bai, an electrical engineering graduate student, and Everett Meyer, medical student. The PANDA system uses small speakers installed in the front wheel wells and under the back fender; a little box (the prototype sits in front of the gear shift) sends the sound to the speakers. The system designers say the noise isn't audible from inside the car; from the outside, it's just a little quieter than a normal combustion engine. You can hear it for yourself here or below.